The first diesel-electric hybrid bus in Shanghai was tested Tuesday as a model of energy-efficiency and the future of transportation that currently is dirty and polluted.

The second such bus is on its way to the city, and if successful, more such buses will be introduced to the local bus fleet, said Dazhong Transportation (Group) Co, operator of the 92B line where the new model is operating.

The hybrid type uses 30 percent less fuel and the emission is 70 percent less than ordinary models.

But the high price, around 700,000 yuan (US$87,516), doubling the common type, makes it difficult for bus companies to decide.

The new type of bus has two driving system, a diesel-fueled engine which is one third smaller than that of a common bus in terms of its power, and a battery.

The battery can be charged by absorbing energy from the engine when the driver reduces the speed or applies brakes.

The two systems can work together or separately to propel the bus.

Officials expect the government to subsidize the use of such environmentally-friendly buses.

The city has listed reducing car emissions as part of its three-year environmental plan, which runs from this year through 2008.